The function can be used to write an partition layout to the block device
based on its cdev layout. Only cdevs with flag DEVFS_PARTITION_IN_PT set
get written. The function also adds an static offset of 0x200000 to
ensure the mbr and bootloader will not be overwritten.
Signed-off-by: Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx>
---
common/partitions/dos.c | 71 +++++++++++++++++++++++++++++++++++++++++++++++++
include/disks.h | 1 +
2 files changed, 72 insertions(+)
diff --git a/common/partitions/dos.c b/common/partitions/dos.c
index 5f08e25..d7fa538 100644
--- a/common/partitions/dos.c
+++ b/common/partitions/dos.c
@@ -256,6 +256,77 @@ static void dos_partition(void *buf, struct block_device *blk,
&dsp->signature, "%08x", dsp);
}
+static inline void hdimage_setup_chs(unsigned int lba, unsigned char *chs)
+{
+ const unsigned int hpc = 255;
+ const unsigned int spt = 63;
+ unsigned int s, c;
+
+ chs[0] = (lba/spt)%hpc;
+ c = (lba/(spt * hpc));
+ s = (lba > 0) ?(lba%spt + 1) : 0;
+ chs[1] = ((c & 0x300) >> 2) | (s & 0xff);
+ chs[2] = (c & 0xff);
+}
+
+int write_dos_partition_table(struct block_device *blk, struct list_head *cdevs)
+{
+ char part_table[6+4*sizeof(struct partition_entry)+2];
+ struct cdev *cdev, *ct;
+ void *buf;
+ int ret;
+ int n = 0;
+ char *ptr;
+
+ /* prepare partition table entry */
+ ptr = part_table;
+ memset(ptr, 0, sizeof(part_table));
+
+ /* skip disk signature */
+ ptr += 6;
+ list_for_each_entry_safe(cdev, ct, cdevs, devices_list) {
+ if ((cdev->flags & DEVFS_IS_PARTITION) &&
+ (cdev->flags & DEVFS_PARTITION_IN_PT)) {
+ struct partition_entry *entry;
+ entry = (struct partition_entry *)
+ (ptr + n * sizeof(struct partition_entry));
+
+ /* add static offset to skip the mbr and bootloader */
+ cdev->offset += 4096 * SECTOR_SIZE;
+
+ entry->type = 0x83;
+ entry->partition_start = cdev->offset / SECTOR_SIZE;
+ entry->partition_size = cdev->size / SECTOR_SIZE;
+
+ hdimage_setup_chs(entry->partition_start,
+ entry->chs_begin);
+ hdimage_setup_chs(entry->partition_start +
+ entry->partition_size - 1,
+ entry->chs_end);
+ n++;
+ }
+ if (n == 4)
+ break;
+ }
+
+ ptr += 4 * sizeof(struct partition_entry);
+ ptr[0] = 0x55;
+ ptr[1] = 0xaa;
+
+ buf = read_mbr(blk);
+ if (!buf)
+ return -EIO;
+
+ /* manipulate block with prepared partition table */
+ memcpy(buf + 440, part_table, sizeof(part_table));
+
+ ret = write_mbr(blk, buf);
+
+ free(buf);
+
+ return ret;
+}
+
static struct partition_parser dos = {
.parse = dos_partition,
.type = filetype_mbr,
diff --git a/include/disks.h b/include/disks.h
index 9932750..432fb23 100644
--- a/include/disks.h
+++ b/include/disks.h
@@ -37,5 +37,6 @@ struct partition_entry {
} __attribute__ ((packed));
extern int parse_partition_table(struct block_device*);
+extern int write_dos_partition_table(struct block_device *blk, struct list_head *cdevs);
#endif /* DISKS_H */
--
2.9.3
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